Catastrophic failure

Last weekend, I attended a launch event hosted by my local rocket club. It was a great experience, and I enjoyed watching others launch a ton of rockets, large and small. A launch report that the club sent out afterwards said that there were 111 total flights, ranging from motors sized 1/2 A up through G. (It was a low and mid power launch, so nothing higher than that.)

Rockets set up on range on grassy field
Rocket range

Something else made the day particularly memorable: my rocket self-destructed.

But first, a little background.

A rocket launch can go wrong in a lot of different ways. A LOT. One of the most common issues is a failure of the recovery system – for example, the parachute fails to deploy properly, and the rocket comes crashing down. But a rocket can be constructed perfectly and the launch can still end in disaster if the motor or engine malfunctions. Motors are designed by people with advanced degrees in chemistry and engineering, and constructed with expensive equipment in large facilities (with hefty insurance policies), but they’re effectively just small explosive devices and things can understandably go wrong at times. When a motor fails, it’s termed a “catastrophic failure,” commonly referred to in the rocket-launching business as a “cato.”

This launch day had an unusually large number of catos, including during one of my own launches.

A sad day - me holding the crumpled rocket
A sad day

I flew the “Mean Machine” twice, and the first time everything went well. It launched smoothly, flew high, the parachute deployed, and it drifted back to the ground. I recovered it and prepped it for a repeat performance.

But on the second launch, the motor suffered a catastrophic failure. It seems that the propellant inside the motor somehow exploded out of the casing, which meant a small fireball shot upwards through the rocket, superheating the body tube and blowing off the nose cone prematurely (and shearing off the parachute’s shock cord, severing it from the rest of the rocket). The body tube, which is normally very hard and difficult to bend, crumpled from the extreme heat. It then quickly cooled, and is now frozen and unbendable in its current sad and broken state.

Crumpled rocket on floor
Crumpled rocket

I’m reassured that this “cato” was solely due to a defective motor and not my shoddy construction of the rocket, and I’m further encouraged by the fact that something similar happened to several other people on the range that day. (Not that I’m happy it happened to anyone else, but at least we could commiserate.)

And to be honest, it’s not really a big deal – the fins are totally fine. With a little work, I can cut away the damaged part and re-join the two halves of the tube into a single straight rocket again. It’s a good learning experience, and it makes for a great video clip, too, which I’ll post shortly.

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